1. Field of the Invention
This invention relates to N,N'-alkylene-bis-tetrahalophthalimides and more particularly relates to an improved process for preparing them.
2. Description of the Prior Art
As taught in U.S. Pat. No. 3,873,567 (Cyba), British Pat. No. 1,287,934 (Raychem), and Sydney M. Spatz and Herman Stone, "Some N-Substituted Tetrabromophthalimide Fire-Retardant Additives," INDUSTRIAL AND ENGINEERING CHEMISTRY PRODUCT RESEARCH AND DEVELOPMENT, Volume 8, pp. 397,398 (1969), N,N'-alkylenebis-tetrahalophthalimides having utility as flame retardants can be prepared by reacting a tetrahalophthalic anhydride with a diaminoalkane in an organic solvent medium. However, since organic solvents have the disadvantages of being costly and flammable, it would be desirable to find an alternative method of preparing the compounds.